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Police forces across the United Kingdom effectively campaigned to deploy a face scanning system acknowledged as biased against females, youths, and members of ethnic minority groups, after complaining that a less biased version generated fewer potential suspects.

The Technology in Practice

UK forces utilize the police national database (PND) to carry out searches using historical face recognition. This procedure entails matching a “probe image” of a person of interest against a repository of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was flawed. This acknowledgment came after a review by the government's National Physical Laboratory determined it incorrectly matched people of Black and Asian heritage and females at significantly higher rates than white men. The ministry stated it “took steps on the findings”.

“It prompts the issue of whether this technology only becomes effective if users accept discrimination in race and sex. Operational ease is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been known about for more than a year. Furthermore, police forces argued to overturn an earlier ruling that was designed to mitigate the problem.

Police bosses were notified of the system's bias in September 2024. The Home Office-commissioned laboratory study found the system was had a higher probability to produce incorrect matches for images depicting females, Black people, and those aged 40 and under.

A Policy U-Turn

In reaction, the national police leadership body ordered that the confidence threshold required for potential matches be raised to a point where the disparity was greatly diminished.

However, this directive was reversed the next month after forces complained that the adjusted system was producing fewer “investigative leads”. Internal records show the stricter setting cut the number of queries resulting in potential matches from over half to a just under 15%.

Profound Inequalities

Although the Home Office and NPCC declined to specify what setting is now in operation, the recent NPL study found the system could generate incorrect matches for Black women nearly a hundred times more frequently than for white women at certain settings.

The Home Office stated on these results: “Our evaluation found that in a limited set of circumstances the software is has a greater tendency to incorrectly include some population segments in its search results.”

Balancing Utility and Fairness

Describing the effect of the brief increase to the system's accuracy setting, the NPCC documents note: “The change greatly lessens the effect of bias across protected characteristics of race, generation and sex but had a substantially detrimental effect on operational effectiveness”. The documents add that forces argued that “a once effective tactic now delivered results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has opened a two-and-a-half-month public review on its plans to widen the use of biometric scanning systems. The minister for police the relevant minister has labeled the technology as the “most significant advance since genetic fingerprinting”.

Criticism from Advisors and Monitors

The chair of a police oversight board, chair of the advisory panel for the national policing equality strategy, commented: “There was scant consideration through race action plan meetings of the facial recognition rollout despite obvious cross-over with the strategy's goals.

“This disclosure demonstrate once again that the pledges to combat discrimination policing has made through the race action plan are not being translated into wider practice. Our reports have cautioned that new technologies are being implemented in a context where ethnic inequalities, inadequate oversight and poor data collection already persist.

“Any use of facial recognition must adhere to rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson said: “We takes the findings of the study with utmost gravity and we have implemented changes. A new algorithm has been independently tested and acquired, which has no statistically significant bias. It will be trialled in the coming months and will be subject to evaluation.

“Our priority is ensuring public safety. This gamechanging technology will support police to apprehend and prosecute offenders. There is human involvement in each stage of the process and no arrest or charge would be pursued without trained officers meticulously examining the output.”